branfrog

When I first purchased my Eheim canister filter it came with the standard poly floss filter, bio-media and a carbon filter. In the packaging for the carbon filter there was a piece of paper that stated: the carbon filter is to be used for new tanks only and for only 2 weeks as it is ineffective after this period of time. The line that still rings in my head is "to be used for new tanks only"...

I now use HBH 'cut your own' carbon filters as they are cheaper. The carbon filters give me a sense of well being that my water is being completely filtered, but i am wondering if this is overkill and/or not recommended.

Also, I only change the carbon filter once a month when i change out the poly filter. I'm thinking even though the carbon isn't working after 2 weeks, the carbon fabric at least provides 1/4" of additional filter fabric, but I am wondering if the old carbon filter is prone to growing bad stuff?

So my questions are:

Should carbon filters only be used in special cases such as new aquariums or to fix discolored or odorous waters?

and

Is it bad to keep a carbon filter in a canister filter longer than the recommended 2 weeks?

BJP

No, tanks can benefit from carbon use throughout their existence.

Not if it's cleaned regularly. After it's useful chemical life it serves as bio housing and in the case of the pads, mechanical filtration.

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branfrog

Thanks BJP!

I suspect something was lost in the Ehiem carbon filter note as it was translated from the manufacturer's German language to English. The fish and plants seem to be loving the crystal clear water!

jd@ga

Carbon will leach out impurities after the carbon is full and dated. I personally only use it in hob filters and in a reactor. That way it is easily changed, added, and removed when needed.

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Jay

I think we hobbyists need to be careful about the relationship between our observations and conclusions. This is anecdotal information and can lead others to misadventure <-

The use of Activated Carbon = Crystal clear water. While it may be a contributing factor, it is not the sole reason. Further, Crystal Clear water can imply excellent water quality, when in Truth, Activated Carbon has no significant impact on TDS and some other DOCs, or Nitrate build up which will impact the health of the tank.

Once exhausted, it is true that there can be some very small surface release of impurities, the problem is that it is impossible to tell when that will happen. One day, one week, its a complete guess. This release is really only of concern in critical filtration systems like drinking water, and is closely monitored.

Regards,
Jay